Frankel shared a photo of Shields and her late dog Cookie cuddling on a bed, sleeping peacefully. She captioned it, "Rest In Peace my sweet babies who gave me endless unconditional love. #nowandforever."

Shields, 51, was found dead of an apparent overdose at Trump Tower Friday, a high-ranking law enforcement source told News 4. Autopsy results are pending. PEOPLE reported Frankel attended a funeral for him Monday on Long Island.

Shields and Frankel had known each other for more than three decades, but didn't start dating until 2016. Phases of their on-again off-again relationship were featured in Season 10 of "The Real Housewives of New York City."

Frankel opened up about it earlier this year on "Steve Harvey," describing a shift back toward friendship.

“I’ve been with someone on and off for years,” Frankel told Harvey in May, without identifying Shields by name. "It’s like a partnership where if we’re not being teammates and it’s not working and one man is down, then the other man is down."

"We’re trying to really kind of be good partners and be good teammates and I think relationships oddly are — and this sounds cold — but a little bit like business," she added. "If both people aren’t happy about it but slightly uncomfortable and giving up something or giving in [to] something, it doesn’t work. So both partners have to say, ‘All right, I’m in it for this.'"

Shields separated from his wife Jill in 2016, when the relationship with Frankel started. They had been married for 26 years prior, PEOPLE reported.

These 20 Colleges Give Students the Best Financial Aid Packages in the Country, Report Says

In a statement to News 4 last week, Jill Schwartzberg Shields said the family was devastated by the loss of their "loving father and friend."

According to a 2016 E! News article, Shields received a master's degree in public relations, but became prominent in the banking world — serving as the CEO of LawCash, a pre-settlement funding company, since its inception in 2000. He was also a driving force in the creation of American Legal Finance Association (ALFA). Additionally, he co-founded and was chairman of YieldStreet, which is a crowdfunding company, and Esquire Bank.

These Are the Most Charming Small Towns in Each State, According to a Report